a.rb

diff --git a/core/lib/Drupal/Core/Entity/Entity.php b/core/lib/Drupal/Core/Entity/Entity.php
index cf18d55..0b47db2 100644
--- a/core/lib/Drupal/Core/Entity/Entity.php
+++ b/core/lib/Drupal/Core/Entity/Entity.php
@@ -135,7 +135,14 @@ public function bundle() {
   public function label() {
     $label = NULL;
     $entity_type = $this->getEntityType();
-    if (($label_callback = $entity_type->getLabelCallback()) && is_callable($label_callback)) {
+    $label_callback = $entity_type->getLabelCallback();
+
+    // If the callback starts with '::' assume it is a method on the entity.
+    if ($label_callback && strpos($label_callback, '::') === 0) {
+      $label_callback = array($this, str_replace('::', '', $label_callback));
+    }
+
+    if ($label_callback && is_callable($label_callback)) {
       $label = call_user_func($label_callback, $this);
     }
     elseif (($label_key = $entity_type->getKey('label')) && isset($this->{$label_key})) {